Recently, the wide use of smart phones has increased the use of pressure sensors capable of sensing pressure in a height direction. A piezo-resistive pressure sensor for detecting a variation in a resistance value of a piezo-resistive element as a variation in pressure has been proposed.
For example, there is known a pressure sensor including a base substrate, a cap substrate having a concave portion and bonded to the base substrate to form a space between the concave portion and the base substrate, a membrane formed within the space by using a portion of the base substrate, and an impurity diffused region formed in the membrane and serving as a pressure sensor element. In the pressure sensor, the membrane is displaced according to pressure applied thereto and a change in a resistance value of the impurity diffused region based on the displacement is measured to detect pressure.
However, characteristics of the piezo-resistive element may be varied depending on a change in an ambient temperature, and thus, detecting pressure has deviations when the ambient temperature is changed. Thus, for the pressure sensor using the piezo-resistive element, correction is essential in detecting pressure.